2. Implement Main program structure

[LobsterLobsterski]

convertCore(array<str> paths, HashMap<str, byte> conversionTypes, str outputFolder):
    for each path in paths:
        type = getTypeByFileExtension(str path)
        switch (type):
            case 0:
               compressImg()
            ...
            default:
               paths = getPathsFromDir(path)
               convertCore(paths, conversionTypes, outputFolder+path)